That youngster in turn becomes an upperclassman, only himself to be upstaged by the newer, en vogue version of the talented youngster—the role he had hitherto played.

For a brief second toward the end of the 2013 season, it appeared that the cycle might stop. T.J. Yeldon was finishing his sophomore year and had asserted himself as by far the best back on the roster. During his junior season in 2014, he would no doubt become the first player since Saban's arrival to play "workhorse back" more than once.

And then, inexplicably, the 2014 Sugar Bowl happened.

The dawning of Derrick Henry happened.

A true freshman who entered the game with just 27 touches on the season, Henry stoked a brief comeback for Alabama with eight carries, 100 rushing yards, one rushing touchdown and a 61-yard touchdown reception in the 45-31 loss to Oklahoma.

Even in defeat, what Henry did in the Superdome felt important; like a changing of the guard. Both of his scores came with Alabama trailing by 14 points—i.e. made it a one-possession game—and neither looked better on paper than it did on the field.

They were plays even Marshawn Lynch would call "Beast Mode":

After ending the season on such a dramatic high, Henry now enters spring practice with momentum to unseat—or at the very least earn equal playing time as—Yeldon in 2014.

Provided both stay healthy, neither will become an afterthought in this offense. Especially with a new quarterback being broken in, there will be enough carries to go around. However, even in a "1a. and 1b." split, there can only be one alpha and one beta.

If Henry wants to be the former, he would be wise to pretend the Sugar Bowl never happened. That may sound like curious advice—it's likely one of his fondest memories—but it's practical after the learning curve Henry endured as a freshman.

If he dwells on his breakout and reads too many of his press clippings, Henry might suffer from the same type of complacency that relegated him—a 6'3'', 238-pounder who sprints like a gazelle and happens to be the leading rusher in high school football history—to the bench for so long last season. There's a reason he averaged just 2.3 touches per game before the Sugar Bowl in the first place, and only part of it had to do with the broken leg he suffered in spring camp and spent most of the summer recovering from.

There was a mental part impeding him, too.

"I thought everything would be handed to me," Henry said of his early-season attitude, according to Michael Casagrande of AL.com. "It's a different level here than in high school.

"As the season went on, I got better."

Patrick Semansky/Associated Press

Henry is a once-in-a-generation athlete.

That adjective—"once-in-a-generation"—is one I make an effort to avoid, as it feels hyperbolic and trite. It seems like there are 10 once-in-a-generation athletes playing college football every season, which makes the term, in most cases, a null sort of journalistic paradox.

With Henry, however, there is no other way to describe him.

Because it is so rare, his combination of height, bulk and speed must be described with analogs in lieu of adjectives. It's not just "freakish," it's LeBron James-esque. He's not merely "dominant," he's Jadeveon Clowney playing running back.

(Seriously: re-watch those Oklahoma runs. Who else out there, in any sport, is capable of making their peers look so...small?)

No matter what Henry does this spring, it's unlikely Saban will remove Yeldon from the top of the depth chart. Unless Yeldon does something wrong, he's banked enough credit the past two years to keep his perch at No. 1. That seems fair.

For now.

Once the end of August rolls around, loyalty means far less than skill. Yeldon is set on that front, having come to Alabama with a 5-star pedigree and exceeded expectations since arriving. No matter what happens in 2014, he still has a promising NFL future in front of him.

However, Yeldon has also had chronic fumbling issues, which have manifested themselves in the biggest moments of important games. His ball-handling is a legitimate concern.

That does not bode well for someone who's competing against a superior physical specimen—who will be given a quick hook as soon as he provides one reason. If Yeldon starts putting the ball on the turf, there will be little to keep Henry from passing him.

Physically, Henry has the profile of a future Heisman trophy candidate, and if he works to improve the little things this offseason and runs as purposefully in the fall as he did against Oklahoma, there is no reason he can't contend for that award as early as 2014.

Mark Ingram won it under Saban as a sophomore, and as a runner his ceiling wasn't half as high as Henry's. Beyond just physical talent, Ingram had something impalpable that allowed him to become a great college player.

He had guts.

Henry showed one type of guts in the Sugar Bowl, but now he must show another. He must show the type of guts that persists, that endures from one week to the next. Yeldon has already proven he can compete on a daily basis; this spring and fall, Henry must do the same. He cannot take a single day off.

Even if he doesn't, there's a good chance Yeldon lines up in the backfield for the first snap of the season against West Virginia. Again, after all he has done in Tuscaloosa, that would only seem fair. But he shouldn't get too cozy in that role.